After a vehicle is started, it goes through a “warm-up” period during which component temperatures are increased from an ambient temperature to a steady state operating temperature. A vehicle's transmission fluid is one such component that is heated during the warm-up period. Until the transmission fluid is fully heated, its viscosity is increased and the spin losses of rotating components in contact with the transmission fluid are also increased. The increased spin losses during the warm-up period reduce efficiency and fuel economy of the vehicle.